I have no expertise in Russian history so I will leave that to someone else. Sinn Fein were interested in Russia as a source of recognition. This was part of a general policy of seeking international recognition whereever possible. http://www.difp.ie/ offers digitised transcripts of documents on Irish Foreign policy and the references in this reply refer to this. Dail Eireann (the rebel parliament) sent an envoy, Dr. Patrick McCartan, to Russia with the aim of securing Russian recognition of the Republic of Ireland. In May 1920 there were some discussions about a treaty between the two but this came to nothing (http://www.difp.ie/docs/1920/Russia/33.htm).

The Irish were concerned that if the Russians recognised Ireland too early, it would be used by Britain as propaganda so their policy was to get Russian agreement and reveal it simultaineously with that of other countries (http://www.difp.ie/docs/1920/Recent-developments-Irish-foreign-policy/39.htm) The Russian contact was controversial and was opposed by the Irish envoy to France, George Gavan Duffy, who argued that Lenin was no friend of nationalism and that there could be negative consequences. (http://www.difp.ie/docs/1920/Recent-developments-Irish-foreign-policy/42.htm)

While the Irish were trying to secure recognition from the Russians, they were not necessarily supportive of Lenin's regime. Patrick McCartan the Irish envoy wrote in 1921 "Though it is claimed that the present Government is dictatorship of the Proletariat it is nothing of the kind. It is a dictatorship of the Communist party which represents less than one per cent of the population of Russia; and dictatorship of the Communist party means in reality dictatorship of about half a dozen leaders of the Communist party." (http://www.difp.ie/docs/1921/Russia/89.htm) The Irish revolutionaries were a politically diverse coalition only some of whom had socialist sympathies. Emmet O'Connor's "Reds and the Green: Ireland, Russia and the Communist Internationals 1919–43" (Dublin 2005) describes the fact that the Russian revolution was greeted with enthusiasm at first in Irish left-wing circles. There was also a "Limerick Soviet" in 1919 where left wing revolutionaries and trade unions staged a general strike and effectively ran the city.